California and other states that want to set stricter tailpipe emissions and fuel-efficiency standards may get their chance. Pres. Obama today ordered the U.S. Environmental Protection Agency (EPA) to review its rejection of the Golden State’s application for a waiver to the Clean Air Act, which allows states to enact their own rules if they can prove that they’re tougher than federal pollution standards.

Obama said during his campaign that he’d reverse the waiver rejection, the Associated Press notes, and the agency is expected to do so. New EPA Administrator Lisa Jackson said during her Senate confirmation hearing January 14 that she would “very, very aggressively” review California’s application, which was submitted in 2007 and denied later that year by the Bush administration, which agreed with auto industry arguments that it would be tough to enforce different standards across the country.

After coal plants, cars produce the most Earth-warming carbon dioxide, according to the environmental group National Resources Defense Council (NRDC). The California regs would force automakers to reduce vehicle emissions by a third by 2016—four years before new federal standards take effect. The move would increase fuel efficiency from 27 miles per gallon to 35 miles per gallon in cars and light trucks.

The measure was supposed to take effect this year; 16 other states (accounting for nearly half of the country’s auto market) were set to adopt California’s standards, the Los Angeles Times reports today. (Thirteen states have joined California in its application, and three others say they plan to adopt the stiffer standards if the waiver is granted.) States can follow the federal Clean Air Act standards, or, if California sets stricter ones, they can adhere to those, the New York Times’ Green Inc. blog notes.

Ordinarily, whichever law – state or federal — is stricter takes primacy. While the Golden State has the power to set stiffer air quality standards, the federal government must grant it a waiver to do so under the Clean Air Act. In this case, the auto industry sued California, and the Bush EPA decided to deny California's waiver request.

The industry has viewed the California measure as a way to regulate emissions from cars — and thereby set fuel economy standards — because the easiest way to lower emissions is to build cars that get more mileage. “Applying California standards to several different states would create a complex, confusing and very difficult situation for manufacturers,” Charles Territo, a spokesperson for the Alliance of Automobile Manufacturers, told the New York Times.

But Spencer Quong, a senior analyst at the Union of Concerned Scientists, told the L.A. Times that Obama’s directive puts the industry on notice that his administration ""is going to deliver on its promise to clean up the environment and fight global warming."

Obama also told the Department of Transportation (DOT) today to finalize nationwide regulations requiring the automobile industry to increase fuel-efficiency standards to comply with a 2007 law. The Energy Independence and Security Act of 2007 requires that new cars and trucks meet a standard of 35 miles per gallon – a 40 percent increase over what they are today – by 2020. The Bush EPA failed to issue regulations on those standards.

"For the sake of our security, our economy and our planet, we must have the courage and commitment to change," he said at an event in the East Room of the White House today, according to the AP. "It will be the policy of my administration to reverse our dependence on foreign oil while building a new energy economy that will create millions of jobs."

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